Communication systems are known to transport large amounts of data between a plurality of end user devices. Such end user devices include telephones, facsimile machines, computers, television sets, cellular phones, personal digital assistants, et cetera. As is also known, such communication systems may be a local area network (LAN) and/or a wide area network (WAN). A local area network is generally understood to be a network that interconnects a plurality of end user devices distributed over a localized area (e.g., up to a radius of 10 kilometers). For example, a local area network may be used to interconnect workstations distributed within an office of a single building or a group of buildings, to interconnect computer based equipment distributed around a factory or hospital, et cetera.
As is further known, local area networks may be wired local area networks or wireless local area networks. Wired local area networks typically have a star topology, ring topology, bus topology or hub/tree topology. A local area network that utilizes a star topology includes a private automatic branch exchange (PABX) and/or a private digital exchange (PDX). Such devices switch data among the end user devices and/or data terminal equipment (DTE). Such exchange devices allow for voice and/or data to be conveyed between the end user devices and/or the DTE's of the local area network.
A local area network that utilizes a ring topology passes cable access from one DTE and/or end user device to another until the DTE's and/or end user devices are interconnected in a loop or ring. A local area network that utilizes a bus topology typically employs one of the Ethernet protocols to convey data within the network. As is known, there are a variety of Ethernet protocols that range from conveying data at rates of 10 megabits per second to multiple gigabits per second. A local area network that utilizes a hub technology is essentially a bus or ring topology with the wiring collapsed into a central unit. The central unit includes a set of repeaters that retransmit all of the signals received from DTE's and/or end user devices to other DTE's and/or end user devices on the same bus or in the same ring.
Wireless local area networks have the end user devices and/or DTE's operably coupled to a server via a wireless connection via a portable access unit. The wireless coupling may be a fixed wire placement, such as for application by a personal computer, or via portable devices that roam within the local area network. The wireless local area network may utilize a variety of modulation schemes including spread spectrum, quadrature amplitude modulation, time division multiple access, orthogonal frequency division multiplexing or frequency division multiple access.
A wide area network is generally understood to be a network that covers a wide geographic area. Wide area networks include both public data networks and enterprise wide private data networks. A public data network is established and operated by a national network administrator specifically for data transmission. Such public data networks facilitate the inner working of equipment from different manufacturers. Accordingly, standardizations by the ITU-T have been established for conveying data within public data networks. Currently, there are two main types of public data networks: packet switched public data networks and circuit switched public data networks. For example, the public switched telephone network is a circuit switched public data network while the Internet is a packet switched public data network. Other examples of wide area networks include integrated service digital networks (ISDN) and broadband multiservice networks.
Regardless of the type of communication system (e.g., LAN or WAN), each communication system employs a data conveyance protocol to ensure that data is accurately conveyed within the system. All such data conveyance protocols (hereinafter referred to as protocols) are based on layers 1, 2, 3 and/or 4 of the open system interconnection (OSI) 7 layer reference model. As is known, the layers include a physical layer (Layer 1), a data link layer (Layer 2), a network layer (Layer 3), a transport layer (Layer 4), a session layer (Layer 5), a presentation layer (Layer 6), and an application layer (Layer 7).
In general, a protocol is a formal set of rules and conventions that govern how end user devices and/or DTE's exchange information within the communication system. A wide variety of protocols exist, but can be generally categorized into one of four types of protocols: a local area network protocol, a wide area network protocol, network protocol, or routing protocol. Local area network protocols operate at the physical and data link layers and define communication over various local area network media. Wide area network protocols operate at the lowest three layers of the OSI model and define communication over the various wide area media. Routing protocols are network layer protocols that are responsible for path determination and traffic switching. Network protocols are the various upper layer protocols that exist in a given protocol suite. Examples of such protocols include asynchronous transfer mode (ATM), frame relay, TCP/IP, Ethernet, et cetera.
As is further known, communication systems may be networked together to yield larger communication systems, where such networking is typically referred to as internetworking. Internetworking is achieved via internetworking units that allow communication networks using the same or different protocols to be linked together. The internetworking units may be routers, gateways, protocol converters, bridges, and/or switches.
Routers are intelligent devices that connect like and unlike local area networks. They also connect to metropolitan area networks and wide area networks, such as X.25, frame relay and/or ATM based networks. Accordingly, routers operate at the physical layer, link layer and/or network layer of the OSI model to provide addressing and switching. In addition, routers may also operate at Layer 4, the transport layer, in order to ensure end-to-end reliability of data transfers.
A gateway provides an entrance and an exit into a communication system. For example, a gateway may be a connection between local area networks, between a local area network and a wide area network, or between wide area networks. Accordingly, a gateway is a node on both networks and provides mapping to all 7 layers of the OSI model. Thus allowing interfacing between 2 incompatible systems (e.g., mail system and data file transfer system) to be interconnected.
A bridge is a data communications device that connects two or more network segments and forwards packets between them. A bridge operates at the physical layer of the OSI reference model and serves as a physical connection between segments, amplifies carrier signals and buffers data during periods of network congestion. As is known, bridges are protocol specific (e.g., supports only one of Ethernet, token ring, et cetera).
A switch works at the physical and data link layers of the OSI reference model with emphasis on the data link layer. A switch reads incoming data (e.g., voice or data) to determine a destination address, or addresses. Based on each address, a transmission path is set up through a switch matrix between an incoming communication port and an outgoing physical communication port. In addition, switches include buffering to hold data packets until the necessary resources are available to allow packets to be forwarded.
A protocol converter is a communication device that translates a binary data stream from one protocol format into another according to a fixed algorithm. Accordingly, the protocol converter converts data from one protocol to another and may be incorporated into a switch, a bridge, a router and/or a gateway.
As is also known, the internetworking unit processes data in accordance with the protocols of the networks it is coupled to. Such data includes a header, or overhead, section and a data payload section. The header section includes the addressing, routing, packet identification, et cetera that is particular to a certain protocol, which ensures proper transporting of the data within the network. For example, the overhead section of an Ethernet frame includes a preamble, destination address, source address, type/link field, and frame check. If the data conveyance is via the Internet and/or a local area network, the data section of the Ethernet frame will include a TCP/IP frame, or packet, which, in itself, includes an overhead section and a data section. As is further known, the bit rate of the overhead section may be slower than the bit rate of the data section such that up to 80% of an internetworking units bandwidth is consumed by conveying overhead information. As such, the throughput for the actual data is limited due to the overhead being conveyed.
To provide a minimum level of interconnection between communication systems, each type of internetworking unit processes millions of bits of data per second. Accordingly, each internetworking unit includes high-speed interfaces to efficiently input and output data. Such interfaces, in processing circuitry, are implemented in integrated circuits that are mounted on printed circuit boards. A group of printed circuit boards are mounted on a motherboard and placed in a rack.
Since each internetworking unit is the conduit for data flow between communication systems, the speed of the internetworking unit is critical to avoid bottlenecking of the internetworking process. As is known, bottlenecking occurs when one device is in the critical path of data conveyance and its speed is the limiting factor for conveying data over the path.
In an effort to meet the ever-increasing challenges of improving speed within an internetworking unit, each internetworking unit includes an increasing number of racks, which includes an increasing number of printed circuit boards (PCBs), which in turn includes an increasing number of integrated circuits that are becoming more and more complex. The racks and PCB's are coupled together using coaxial cables, fiber optics, connectors, and/or wires. The integrated circuits on a printed circuit board are operably coupled together via copper traces (e.g., FR4 connections). Data is transported over these interconnections using the latest transmission protocols, such as 10 gigabits per second Ethernet standards. While this provides greater data throughput than earlier generations of internetworking units, there are still limitations. For example, at 10 gigabits per second, the distance that data can travel over a printed circuit board trace, wire and/or coaxial cable is limited to approximately 45″. If the data must traverse a connector, the distance is even less. One solution to overcome the distance limitation is to use multiple lower rate paths to convey the data, which has the inherent issues of additional circuitry to transmit the data, synchronization of data transmissions and data recovery.
Therefore, a need exists for a method and apparatus that improves data throughput within networks and/or between networks.